We study history by Era because

An era is a span of time defined for the purposes of chronology or historiography, as in the regional eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. We study history by era to make it easy to divide periods in the past.

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please mark it the brainliest!

- a.) african slaves and indentured servant’s

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